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Nitrogen May Increase Bt Levels in Corn

February 6, 2003

Source: American Society of Agronomy

MADISON, WI, February 6, 2003 - Scientists at the USDA-ARS, Jamie Whitten, Delta States Research Center in Stoneville, MS, have found that Bt concentrations in young corn plants are directly influenced by the amount of nitrogen fertilizer applied at planting. The research is published in the January-February 2003 issue of Agronomy Journal.

Hybrid corn cultivars genetically modified to have the Bt-producing gene synthesize special proteins that can kill the larva of certain corn insect pests, such as fall armyworm and southwestern cornborer. The Bt corn hybrids provide farmers with an alternative to avoid costly damage from feeding by these pests without the use of pesticides.

Two corn hybrids with different types of Bt toxin were used in the experiment. These hybrids were grown in pots in the greenhouse and two plantings were made. A common fertilizer used to grow corn, ammonium nitrate, was blended into the potting mixture prior to planting. Rates of fertilizer used in the experiment represented zero, low, normal, and high amounts of nitrogen used to grow corn. Pots were carefully watered to avoid leaching of the fertilizer during the experiment. When the plants had five fully extended leaves, sample tissues were taken to determine the Bt and nitrogen concentrations of the plant.

The levels of Bt toxin and total nitrogen in the plant steadily increased as the amount of nitrogen fertilizer increased. Both Bt hybrids responded the same to increasing levels of nitrogen fertilizer.

One of the two scientists who conducted the research, Dr. H. Arnold Bruns said, "The effectiveness of Bt hybrids to avoid insect damage may be dependent on the amount of nitrogen fertilizer applied to the crop early in the growing season. Further research will be necessary to determine if similar effects to Bt concentrations can be found in more mature corn. These findings could affect the way we manage nitrogen fertilizer applications to Bt hybrid corns".

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Agronomy Journal, http://agron.scijournals.org is a peer-reviewed, international journal of agriculture and natural resource sciences published six times a year by the American Society of Agronomy (ASA). Agronomy Journal contains research papers on the subjects of soil and plant relationships; crop science; soil science; crop, soil, pasture, and range management; integrated agricultural systems. turfgrass; agroclimatology and agronomic modeling; environmental quality; and integrated pest management.

The American Society of Agronomy (ASA) www.agronomy.org, the Crop Science Society of America (CSSA) www.crops.org and the Soil Science Society of America (SSSA) www.soils.org are educational organizations helping their 10,000+ members advance the disciplines and practices of agronomy, crop and soil sciences by supporting professional growth and science policy initiatives, and by providing quality, research-based publications and a variety of member services.